Tank with reinforced bottom joint

ABSTRACT

A tank includes a bottom portion with an upwardly extending annular flange having a reduced thickness at an end portion as compared to a lower portion. A generally cylindrical sidewall portion has an end portion disposed within the annular flange and forms a joint therewith. An internal overlaminate piece is bonded about an inner circumference of the joint. An external overlaminate piece is bonded about an outer circumference of the joint.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. Provisional Patent Application No. 61/790,845 filed Mar. 15, 2013, the disclosures of which are incorporated herein in their entirety by reference.

BACKGROUND

This relates in general to tanks for storage or transportation of materials or material contained therein.

One know type of tank includes a middle section capped with top and bottom sections. The top and bottom sections are joined to the middle section, for example, with laminated joints. Such tanks may include hoop segments to strengthen or reinforce these joints.

Generally, tanks having a seam at the bottom of a tank are subject to an increased risk of structural failure as compared to those tanks that do not have a seam at the bottom of the tank.

SUMMARY

This relates more specifically to a tank including a bottom portion with an upwardly extending annular flange having a reduced thickness at an end portion as compared to a lower portion. A generally cylindrical sidewall portion has an end portion disposed within the annular flange and forms a joint therewith. An internal overlaminate piece is bonded about an inner circumference of the joint, where internal is in relation to the interior of the tank. An external overlaminate piece is bonded about an outer circumference of the joint, where external is in relation to the exterior of the tank.

The end portion of the upwardly extending annular flange may be tapered. The end portion of the generally cylindrical sidewall portion may be tapered.

A structural multidirectional glass fabric may be disposed within the bottom portion. A structural multidirectional glass fabric may disposed within or as part of the internal overlaminate piece and/or the annular flange. A structural multidirectional glass fabric may be disposed within or as part of the external overlaminate piece and/or the end portion.

The tank may further include a top portion disposed about a second end of the generally cylindrical sidewall portion. At least one valve may be disposed within the top portion, and at least one nozzle may be disposed in the top portion. In at least one embodiment, the top portion may comprise a thief hatch, and the valve may be disposed within the thief hatch. Additionally, the tank may further include at least two lifting lugs that may be disposed in the top portion.

The tank may further include a manway disposed in the sidewall portion between the first end portion and the second end portion. The manway may include a layer of overlaminated structural multidirectional glass fabric

A method of manufacturing any such tank is also disclosed.

Various aspects will become apparent to those skilled in the art from the following detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a tank.

FIG. 2 is a back perspective view of the tank of FIG. 1.

FIG. 3 is an exploded view of the tank of FIG. 2.

FIG. 4 is a view of the tank of FIG. 1 partially cut away.

FIG. 5 is an enlarged view of a portion of FIG. 4.

FIG. 6 is a front view of the manway of the tank of FIGS. 1-5.

FIG. 7 is a cross-sectional view of the manway of FIG. 6 taken along line a-a.

DETAILED DESCRIPTION

Embodiments relate to a tank and a method of making a tank. With reference to the drawings, like reference numerals designate similar or corresponding parts throughout the several views. However, the inclusion of like elements in different views does not necessarily mean that any given embodiment necessarily includes requires such elements or that all embodiments include such elements.

Referring now to the drawings collectively, there is illustrated in FIG. 1 a tank 100. The tank 100 includes a bottom portion 102 with an upwardly extending annular flange 106. A generally cylindrical sidewall portion 104 has a first end portion 112 and a second end portion 114 with the main sidewall portion 116 extending between the two end portions 112 and 114. A top portion 110 is disposed at or about the second end 114 of the sidewall portion 104. The first end portion 112 of the sidewall portion 104 is joined to the annular flange 106 of the bottom portion 102. The tank 100 may further include a manway assembly 108 for facilitating access to the interior of the tank 100.

As best shown in FIG. 2 the tank may further include a valve 202 disposed within the top portion 110 of the tank 100, and may also further include one or more a nozzles 203 disposed within the top portion 110 of the tank 100. Mounting brackets 200 may be attached to the main sidewall portion 116 of the tank 100. Top portion 110 may also include lifting lugs 204 as shown in FIG. 2.

As best shown in FIG. 3 the tank 100 may includes a bottom portion 102 that is connected to or bonded to the sidewall portion 104 to form a lap joint where the annular flange 106 is bonded to the first end portion 112 of the sidewall portion 104. An internal overlaminate piece 300 is bonded about an inner circumference of the joint, and an external overlaminate piece 302 is bonded about an outer circumference of the joint, where inner or internal is in relation to the interior of the tank 100 and outer or external is in relation to the exterior of the tank 100. A structural multidirectional glass fabric may be disposed within the bottom portion 102. Additional structural multidirectional glass fabric material may be disposed within the joint and/or about the joint to provide the lap joint with additional strength, resulting in increased structural soundness for the tank 100.

As best shown in FIGS. 4 and 5 the sidewall portion 104 may be joined to the bottom portion 102 at a joint 500. The joint 500 may be a lap joint that, for example, may transfer radial and axial loads, thus resulting in increased structural soundness for the tank 100.

In an embodiment, as illustrated in FIG. 5, the bottom portion 102 has an upwardly extending annular flange 106 which terminates in an end portion 506 of the annular flange 106. The sidewall portion 104 has a first end portion 112 which is disposed within the annular flange 106 and forms a joint 500 therewith. An internal overlaminate piece 300 may be bonded about an inner circumference of the joint 500 on the interior of the tank 100. An external overlaminate piece 302 may be bonded about an outer circumference of the joint 500.

The end portion 506 may have a reduced thickness as compared to a lower portion 508 of the annular flange 106. In an embodiment, the end portion 506 of the annular flange 106 can be tapered. The first end portion 112 of the sidewall portion 104 can also be tapered. The bottom portion 102 of the tank 100 may further include a reinforcing fiberglass stitched mat (not shown). The joint 500 may also include one or more reinforcing fiberglass stitched mats. For example, as shown in FIG. 5, a fiberglass stitched mat 502 may form the internal overlaminate piece 300 over the annular flange 106 and the sidewall portion 104. A fiberglass stitched mat may also form the external overlaminate piece 302. As also shown in FIG. 5, a hold down lug plate 504 may be bonded to the external overlaminate piece 302 that surrounds the outer circumference of the joint 500.

Referring to FIG. 6, the manway assembly 108 of the tank 100 is disposed in the sidewall portion 104 between the first end portion 112 and the second end portion 114. The manway assembly 108 includes a flange 600 that can also include one or more manway bolt holes 606 disposed within the flange 600. In the illustrated embodiment, the flange 600 of the manway assembly 108 may be bolted to the sidewall portion 104 of the tank 100 in order to secure the manway assembly 108 to the tank 100. However, other methods may be employed to bond the manway assembly 108 to the tank 100, including bonding using overlapping multidirectional fabrics. The manway assembly includes an interior wall 602 and an exterior wall 604. As best shown in FIG. 7, the manway assembly 108 includes a manway wall 708 that extends from a first end 704 to a second end 706.

In addition to the manway wall 708, the manway assembly 108 may further include a flange 600 (Referring to FIGS. 6-7). For example, as shown in FIG. 7, a cross-section of a manway assembly 108 is shown. In the illustrated embodiment, the manway assembly 108 includes a manway wall 708 having an interior wall 602 and an exterior wall 604, and extending from a first end 704 to a second end 706. The second end 706 terminates in the manway flange 600. The manway flange 600 has interior side 700 and an exterior side 702. The manway may be a commercially available manway manufactured to standards set by ASTM, ASME, ANSI, NBS, or API. Further, the tank 100 and its components may also be manufactured to conform with industry standards for fiberglass tanks and pipes, especially those used in the petroleum industry, set by these organizations. For example, the tank and/or manway may be manufactured to conform with any of the following standards: API 12P, ASME/ANSI B 16.5, ASTM D3299, ASTM D4097, NBS PS 15-69.

A tank 100 according to FIGS. 1-7 may be formed as follows. A bottom portion 102 with an upwardly extending annular flange 106 can be formed, where the annular flange 106 has a reduced thickness at an end portion 506 as compared to a lower portion 508. The annular flange 106 may be tapered at the end portion 506. The end portion 506 may also be recessed or shaped outward in such a way that the tank 100 has a smooth vertical cylindrical surface on the interior of the tank after the bottom portion 102 is bonded to the sidewall portion 104. A sidewall portion 104 can be formed that is generally cylindrical in shape. The sidewall portion 104 has a first end portion 112 and extends upwardly terminating in a second end portion 114. The first end portion 112 may be tapered. A top portion 110 is also formed and bonded to the second end portion 114 of the sidewall portion 104. The annular flange 106 is bonded to the first end portion 112 of the sidewall portion 104. A joint 500 is formed where the annular flange 106 and the first end portion 112 are bonded together. The joint 500 may be at or near the bottom of the tank 100. An internal overlaminate piece 300 is bonded about an inner circumference of the joint 500, and an external overlaminate piece 302 is bonded about an outer circumference of the joint 500. Structural multidirectional glass fabric may be placed between over or around portions of the joint 500 for reinforcement. Examples include placing a layer of fiberglass stitched mat within the internal overlaminate piece 300, and within the external overlaminate piece 302.

The tank 100 may be formed with a manway, although such is not required. For example, the tank as shown in FIGS. 1-7 includes a manway. In FIGS. 1 and 3, a manway assembly 108 is shown. In one method of manufacturing a tank 100 with a manway, an aperture is formed in the sidewall portion 104, and a manway may be fixed about the aperture. A manway assembly 108 may be inserted into the aperture to form the manway. The manway assembly 108 may include one or more layers of structural multidirectional glass fabric, such as fiberglass stitched mat. The manway assembly 108 may be secured to the sidewall portion 104 by applying and bonding overlapping multidirectional fabrics.

A tank 100 of at least one embodiment disclosed herein may include a seam at or near the bottom of the tank 100 that is a lap joint, as opposed to a butt joint, although either may be utilized. Unlike a butt joint, the lap joint transfers and distributes radial and axial stresses by the shear surface of the lap joint and by the inner and outer overlaminate pieces, such as the internal overlaminate piece 300 and external overlaminate piece 302. The internal overlaminate piece 300 and external overlaminate piece 302 may be tapered as well and can extend beyond the joint 500 to increase the overlapped area. These additional features can be included to further increase structural integrity and fatigue resistance. Further, the use of structural multidirectional glass fabric strengthens the seam where the bottom portion 102 of the tank 100 is bonded to the sidewall portion 104. Structural multidirectional glass fabric such as fiberglass stitched mats are generally stronger per unit of thickness than chopped fiber used in conjunction with sprayed resin. The present design allows for increased strength without having a thicker bottom and/or bottom seam as would be required using chopped fiber and sprayed resin.

Referring again to FIG. 3, the bottom portion 102 of the tank 100 may include one or more layers of structural multidirectional glass fabric, such as reinforcing fiberglass stitched mat and/or chopped strand mat. For example, a bottom portion 102 may include one or more of the following: a layer of corrosion resistant resin rich surfacing material, a layer of corrosion resistant resin rich chopped strand mat, a woven rowing stitch mat, a chopped strand mat, and an exterior gel coating. The tank 100 may further include a tank lifting lug assembly 304 and/or a tank hold down lug 306. The tank lifting lug assembly 304 and the tank hold down lug 306 may be formed from steel or galvanized steel or any other suitable metal, metal alloy or other material and bonded to the tank surface by overlapping layers of stitch mat.

Referring to FIGS. 1-3, the tank 100 may, for example, be made primarily of fiberglass reinforced plastic. Such materials are generally corrosion and chemical resistant, are lightweight as compared to steel or other metals, and have good impact strength. An example of a suitable material for forming the tank 100 is a fiberglass-epoxy vinyl ester resin composite, although any other suitable materials may be used. The tank 100 can be manufactured of fiberglass reinforced plastic in a pre-shaped mold or on a form. For example, the sidewall portion 104 and the top portion 110 can be manufactured on a pre-shaped form in one piece, so that the bottom of the tank 100 is left open. Multiple layers of continuous longitudinal and chopped transverse reinforcing fiber strands can be wound around the form with impregnation of structural resin to create the sidewall portion 104 and top portion 110. The top portion 110 can also be prefabricated and co-wound into the main structure. Further, structural filament wound C-glass strands may be circumferentially embedded or added as chopped fibers within the sidewall portion 104, giving the tank 100 additional structural strength.

The bottom portion 102 of the tank 100 can be manufactured separately and then attached to the first end portion 112 of the sidewall portion 104. The bottom portion 102 can be formed by bonding or laminating together layers of structural multidirectional glass fabric and bonding them together with an adhesive agent or bonding agent, such as an epoxy vinyl ester resin or other lamination resin. The bottom portion 102 can further include corrosion barriers such as a layer of corrosion resistant resin rich surfacing material. To form the bottom portion 102, the components of the bottom portion 102 can be layered over a male mold, for example, by beginning with a corrosion barrier material, and adding additional layers of reinforcing fiberglass, and bonding the layers together with an adhesive agent or bonding agent. The bottom portion 102 can then be joined to the sidewall portion 104 at the first end portion 112 of the sidewall portion 104. Referring to FIG. 3, the internal overlaminate piece 300 and external overlaminate piece 302 that are bonded to the joint formed by the sidewall portion 104 and annular flange 106 may include, for example, a bidirectional reinforced multilayered band that provides support to the joint.

While principles and modes of operation have been explained and illustrated with regard to particular embodiments, it must be understood, however, that this may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope. 

What is claimed is:
 1. A tank comprising: a bottom portion with an upwardly extending annular flange having a reduced thickness at an end portion as compared to a lower portion, a generally cylindrical sidewall portion having an end portion disposed within the annular flange and forming a joint therewith, an internal overlaminate piece bonded about an inner circumference of the joint, and an external overlaminate piece bonded about an outer circumference of the joint.
 2. The tank according to claim 1, wherein the end portion of the upwardly extending annular flange is tapered.
 3. The tank according to claim 1, wherein the end portion of the generally cylindrical sidewall portion is tapered.
 4. The tank according to claim 1, further comprising a reinforcing fiberglass stitched mat disposed within the bottom portion.
 5. The tank according to claim 1, further comprising a reinforcing fiberglass stitched mat disposed within one of the internal overlaminate piece and the annular flange.
 6. The tank according to claim 1, further comprising a reinforcing fiberglass stitched mat disposed within one of the internal overlaminate piece and the end portion.
 7. A tank comprising: a bottom portion with an upwardly extending annular flange having a reduced thickness at an end portion as compared to a lower portion, a generally cylindrical sidewall portion having a first end portion and a second end portion with a main sidewall extending therebetween, the first end disposed within the annular flange and forming a joint therewith, a top portion disposed about the second end. an internal overlaminate piece bonded about an inner circumference of the joint, and an external overlaminate piece bonded about an outer circumference of the joint.
 8. The tank according to claim 7 further comprising a manway disposed in the sidewall portion between the first end portion and the second end portion.
 9. The tank according to claim 7, further comprising a reinforcing fiberglass stitched mat disposed within the bottom portion.
 10. The tank according to claim 7, further comprising at least one valve disposed in the top portion.
 11. The tank according to claim 7, wherein the end portion of the annular flange is tapered.
 12. The tank according to claim 7, where in the first end portion of the generally cylindrical sidewall portion is tapered.
 13. A method of manufacturing a tank comprising: forming a bottom portion with an upwardly extending annular flange having a reduced thickness at an end portion as compared to a lower portion, forming a generally cylindrical sidewall portion having a first end portion and extending upwardly to a second end portion, forming a top portion, bonding the top portion to the second end portion of the sidewall portion, bonding the annular flange to the first end portion of the sidewall portion to form a joint, bonding an internal overlaminate piece about an inner circumference of the joint, and bonding an external overlaminate piece about an outer circumference of the joint.
 14. The method of claim 13, further comprising: placing a layer of fiberglass stitched mat within the internal overlaminate piece and the annular flange.
 15. The method of claim 13, further comprising: placing a layer of fiberglass stitched mat within the internal overlaminate piece and the first end.
 16. The method of claim 13, further comprising: forming an aperture in the sidewall portion between the first end portion and the second end portion, and fixing a manway about the aperture. 